Process of obtaining metals and alloys by reduction.



No. 883,594. PATENTED MAR. 31, 1908.

E. VIEL. PROCESS OF OBTAINING METALS AND ALLOYS BY REDUCTION.

APPLICATION FILED OUT. 31, 1906.

K W g Y ,1 I J o 2/ /fi 0,32% m0 (my mi di, film/WK m wm tions of themixture should then be suc UNITED STATES PATENT OFFICE.

EMILIEN'VIEL, OF RENNES, FRANCE.

PROCESS OF OBTAINING METAIiS AND ALLOYS BY REDUCTION.

Specification of Letters Patent.

Patented March 31, 1908.

Application filed October 31, 1906. Serial No. 341,494.

mium, etc. by reduction of their oxids.

Hitherto numerous attempts have been made by scientists and engineers toreduce in z decomposition temperature of the oxid the electric furnacethe refractory oxids, such as alumina, silica, magnesia, and chromiteetc. for the purpose of obtaining the corresponding metals. Theseattempts have not been successful because the inventors who havetakenupthis question have failed to realize the necessary conditions in theirprocesses and their apparatus. The first of these conditions is to raiseto the formation temperature, that is to say approximately to thedecomposition temperature, all the compounds of the known metals, and atthis moment to cause the intervention of a body capeble of absorbing theoxygen, if an oxid is eing treated, the chlorin, if a chlorin is beingtreated and so forth. In the most general case where oxids have to betreated, the appropriate reducing agent is carbon. In or er to complywith this condition, it is necessary to have an ap aratus permitting ofobtaining a sufficient y hi. h tem erature. The second condition is toform be orehand with the reducing agent, such as carbon, preferably inthe form of charcoal, as perfect a mixture as possible, which result maybe obtained by employing these bodies in a very finely pulverizedcondition the pro oras are indicated by the equations of the chemicalreaction, for example In the third place care should be taken that whenthe mixture has been raised to such a temperature that decomposition hastaken place, the metal liberated should immediately be conducted fromthe excessively hot decomposition zone into another relatively cold zonewhich is at a temperature lower than the volatilization temperature ofthe separatedmetal. For example, in the case of alumina, which isdecomposed by carbon at a temperature of about 3 ,000 and gives .so byrefractory walls or'coverings f of a proaluminium, the arrangement mustbe such that immediately after its separation the aluminium is conductedinto a zone at a temperature lower than 800, above which temperaturealuminium volatilizes. In this manner, the combination of thevolatilized metal with oxygen and the formation of the oxid is avoided.Finally the addition of the mixture of oxid and carbon or other reducingagent should take place progressively, that is to say almost in acontinuous manner, and in small quantities, so that it is only necessaryimmediately to raise to the .wit the reducing body, the metal or alloyarising from the decomposition being immediately conducted in an approriate manner into a sufficiently cold zone, t at is to say a zone at atem erature lower than that of volatilization o the metal or of themetals of the separated alloys for the purpose of preventing combinationwith the oxygen of the air.

In the following description, a working furnace which satisfies theconditions enuquantities of the mixture,

merated above is referred to by way of ex- 4 ample and illustrated inthe accompanying drawing in which Figures 1 and 2 represent the saidfurnace in cross-section and in longitudinal section respectively.

The furnace consists essentially of a fusion chamber or crucible a withcarbon walls I) provided with a cover c likewise of carbon,

and with a sole d having' avery steep inclination (say, 25 to 30) thissole having at its lower extremity a water circulation e extendin forexample over about one-third of the Te. This chamber or crucible issurrounded priate thickness, which-may be confine in a sheet metaljacket g. At the lower part of the wall situated at the lowest part ofthe sole, a tapping hole h of appropriate dimensions is formed, topermit of the discharge of the metal; there may also be provided abovethis tapping hole h a second hole which is ordinarily stopped by a plugis of refractory material having a carbon extremity, which hole may beused for inspection purposes and for cleaning the sole.

Two electrodes 71 'i of circular or rectangula r or other cross-sectionenter the chamber or crucible horizontally in line one with the other,or inclined, these electrodes passing through appropriate apertures jformed in the walls f, considerable play being left between the walls ofthese apertures and the electrodes, the said apertures being coveredwith a protecting layer 7c of magnesia. These electrodes i 'i aresupported by appropriate bearings or supports Z, mounted in slideways insuch'a manner that the electrodes may be caused to advance or recede byappropriately rotating the endless screws m by means of hand wheels'11,. The object of this arrangement is to permit of a generalregulation of the arc, and in particular in accordance with the wear ofthe electrodes to which the current is conducted and which it leaves atthe terminals 0 0. In the wall opposite the wall in which the tappinghole is formed, a charging orifice g is provided, and in continuation ofit a conduit r surmounted by a hopper s in which an Archimedean screw protates; this screw is operated by hand, or controlled mechanically inany appropriate manner when the furnace acts with a continuous feed. Inthe median plane perpendicular to the vertical plane assing through theelectrodes and above t is carbon cover 0, two inclined and symmetricalelectro magnets t are jointed on legs u which rest upon projectinghearings on the supports Z. These two electro magnets which may be fedwith current in parallel with that of the electrodes, or from anindependent source, are wound in such a manner that both of them exert arepelling effect upon the are, so as to blow it and bring it nearer tothe sole. As will be understood, the two eiiects of these electromagnets combine themselves in such a manner as to exert a resultanteffect, the direction of which may be varied either by acting upon theinclination of one of the electro magnets or of both at once, or byplacing a greater or smaller number of ampere turns in circuit in one ofthe electro magnets by means of an'appropriate commutator. In thismanner it is pos sible to direct the blown are for the purpose oflocating it in a predetermined zone of the sole, which zone shouldalways be comprised between the points at y marked on the drawmg, thatis to say outside the cold zone, which is situated above the watercirculation e. The reduction process in accordance with this inventionis then carried out with this special furnace in the following mannerThe hopper g is charged with the appropriately proportioned andpulverized mixture duced, and the said mixture is charged con- 7tinuously or in small quantities-on to the sole by rotating the screw12. The mixture falls upon the inclined sole' at its upperextremity andat once reaches the zone of the blown arc the temperature of which maybe taken as about 3000. Under the influence of this high temperature,the oxid fuses and decomposes, and its oxygen combines with the carbonand forms carbonic oxid, which is able to'escape freely owing to theplay left between the electrodes '5 'i and their entrance apertures, orthrough apertures which may be formed in the cover. The liberated metalflows off at once and reaches the cold zone 1 z from which it may becollected in the ingot molds or other appropriate receptacles.

'As in all electro-metallurgic operations, it is advisable topreliminarily heat the furnace until the desired temperature isobtained. During the first operation the liberated metal may combinewith the carbon of the sole in such a manner as to form a refractorycarbid I sole.

It will be understood that by means of the furnace which has beendescribed, it is possible to realize the conditions of the processbecause a continuous or almost continuous admission of the mixture maybe obtained, and owing to the very vigorous blowing of the arc by meansof exceedingly powerful electro magnets, it may be concentrated in agiven zone as close to the sole as desired and a very high temperatureobtained, and further that owing to the inclination of the sole themetal when once it has been separated immediately passes away from theexceedingly hot zone and reaches another relatively cold zone which isobtained as has been indicated by cooling by a water circulation. Asstated above this process and this apparatus ermit of reducing not onlyalumina, but also chromite, magnesia and silica. In this latter case,the operation takes place more readily because the volatilizationtemperature of silicon is 1650 ,that is to say much-higher than that ofaluminium, and the difference between the volatilization temperature andthe'decomposition temperature (2500) is much less. With this process, itis also possible to treat silicates or analogous compounds in order 'toobtain comounds of alloys, such as silico-aluminium, "erro-chroiniumetc. In order to obtain pure aluminium and silicon fromsilico-aluminium, it is necessary to heat the silico-aluminium to 700upon the sole of a reverberatory furnace; the aluminium separates andthe silicon remains as residue. The aluminium thus formed still contains3% of silicon; in order to obtain it pure, the silicon is burned likecarbon in a Bessemer retort.

The apparatus herein described forms the copending application, SerialNo. 399,696, filed October 29th, 1907, and is not herein claimed.

What I claim, is:

1. The process of reducing refractory metallic com ounds consisting insubjecting a 1 mixture 0 said compounds and a reducing agent in acontinuous stream to the heat of an electric are directed thereon withina furnace chamber to effect reduction of the compound to the metallicstate, and then passing the metal so reduced immediately into a coolingzone before it leaves the furnace.

2. The process of reducing alumina to alu- 15 minium consisting insubjecting a mixture of I alumina and carbon in equivalent. roportionsin a continuous stream to the leaf of an electric are directed thereonWithin a furnace chamber to efieet reduction of the alumina toaluminium, and then passing the metal so reduced into a cooling zonebefore it leaves the furnace.

In testimony whereof I have signed this specification in the presence oftwo subscribing witnesses.

EMILIEN V TEL.

Witnesses:

F. FERRET,- R. HIER.

